Treatment of hydrocarbons



Feb. 17, 1942. A.- szAYNA TREATMENT OF HYDROCARBONS Filed Oct. 8, 1938INVENTOR Akvzmvznyww ATTORN EY Patented-Feb. 17, 1942 TREATMENT FHYDROCARBONS Antoni Szayna, Brooklyn, N. Y., assigner to Albert C.Travis, New York, N. Y.

Application October 8, 1938, Serial No. 233,983

(Cl. 19E-24) Claims.

This invention relates to a treatment of hydrocarbon, particularly thosehydrocarbon oils which can be treated in. vapor phase, and to the useand re-use of special contact materials in said process. Moreparticularly, the invention relates to a method of desulfurizing oilsand controlling other concomitant reactions by a contact mass, thesurface of which is adapted to absorb sulfur from sulfur compoundspresent in the`oil,.to a cyclic process in which the contact mass isperiodically regenerated and reemployed in the process.

'I'he presence of sulfur or compounds of sulfur in petroleum coal tarand similar products has long been known, and its removal has long beenlrecognized as a problem of great practical vimportance. In fact a largeportion of the crude petroleum which is available at the present time istoo high in sulfur content to be available for the production of highgrade motor fuelwithout special desulfurizing treatment. One object ofmy invention is directed especially toward this problem; namely toprovide a process for desulfurizing by which the value and quality ofsuch sulfur bearing materials can be improved, although, as will beapparent from the following description, other advantages are attainedby the novel treatment according to my invention which are notnecessarily related to desulfurization.

Another object of the present invention is to desulfurze hydrocarbonoils, e. g., gasoline, while at the same time controlling otheraccompanying reactions toavoid deterioration of the product in otherrespects.

Another object of the invention is to produce a hydrocarbon productwhich is doctor sweet, non-corrosive, stable, of good color, andsubstantially free from tendency to form gums -upon storage.

Another object of the invention is to produce a motor fuel with improvedproperties, including improved lead susceptibility, low gum content andgum formation, high octance rating, etc.

Another object of my invention is to produce a motor fuel of suchimproved properties in high yield and substantially withoutobjectionable byproducts. y

Another object of the invention is to provide a cyclic processwithregeneration of a contact material used in the process, and especiallyone in which any activity which it might otherwise have to deterioratethe product is largely inhibited in the regenerated material.

The invention comprises controlling the conditions, such as selectionand treatment, including regeneration ofthe contact material, amount ofcontact material, velocity of iiow of oil, amount of hydrogen, pressure,temperature and the various other factors which influence the reactions,to obtain the desired sulfur absorption, selective hydrogenation, etc. v

A typical processaccording to my invention consists briefly, invaporizing a high sulfur content gasoline and superheating the vapors,mixing them with a relatively small amount of hydrogen, and passing thismixture, advantageously under pressure, through a desulfurizingcontactor of controlled activity, with the time of contact. dependingupon the length of the contactor and the velocity of gas travel,sumcient to effect the required desulfurization. The treated vaporstogether with unconsumed hydrogen are treated for recovery of thefinished-product and separation of the unused hydrogen, which may berecirculated in further operation of the process. After a period of suchoperation the sulfur absorbing contact material would become more orless saturated with sulfur to the extent that sulfur would begin toappear in the product as hydrogen sulfide. Since more than a trace ofhydrogen sulfide in the liquid product is undesirable, I withdraw fromthe contactor, from time to time, before it is entirely saturated withsulfur,

, at least the most saturated portion of the contactor and replaceV orrenew this portion so as to sustain the sulfur absorbing quality of thecontactor as a whole.

The portion of the contactor which is withdrawn may be regenerated. inthis typical process, by burning oil.' most of the sulfur therefrom, butleaving enough sulfur thereon to effect the desired chemical inhibition,and then reducing with hydrogen so far as to form a renewed contactmaterial for reuse in the process.

Contactor I'have mentioned in thisprocess the contact material (which Isometimes refer to for convenience as the contactor) This is a materialwhich chemically extracts and binds to itself the sulfur from the oil,including sulfur in hydrogen sulfide and in organic compounds, as wellas any free sulfur which may be present. This contactor is in a physicalform with extended surface such as would be adapted to act as a Asurfacecatalyst, and ordinarily its surface will be largely composed of acatalytically active metal, but its activities are so controlled as toavoid undesirable catalysis which otherwise would deteriorate theproduct during the contact and at the temperatures necessary for thedesired eiiicient desulfurization.

I have found nickel to be the most advanta-` geous metal to use for thecontact surface; but I have found that nickel alone, e. g., in the formof metal wool or chips tends to become brittle and to disintegrate inthe course of regeneration; I, therefore, prefer to utilize a nickelsurface on a porous inert carrier of good mechanical strength and otherproperties. Such carriers are already well known in the art ofcatalysis;

among them I may mention as particularly suitable for my reaction,pumice, bauxite, unglazed porcelain, kieselguhr, silica gel, porouscarborundum. To these may be added small amounts of difilcultlyreducible oxides, e. g., oxides of aluminum, chromium, thorium,magnesium, and/or materials for strengthening the carrier, e. g., smallamounts of alkali metal compound such as sodium hydroxide or carbonate,when a silicious carrier is used, or water glass, when a non-siliciouscarrier is used. Materials which also act as catalysts may be used wherethe reactions which they favor are desired. Active clays will ordinarilybe avoided, unless it is desired to catalyze polymerization.

' Inhibitor I may utilize various methods of controlling catalyticactivity, in order to inhibit to the desired extent, according to myinvention, the undesired reactions, while keeping the surface of thecontactor in a form to give rapid and efflcient reaction with the sulfurin the flow of gases or vapors to which it is exposed.

The method which, in general, I have found to be most satisfactory isthe addition to the contactor of a chemical inhibiting agent, such as acatalytic poison, which may be relied upon to reduce the catalyticactivities without a corresponding reduction of the desulfurizingactivity; and thus with the inhibited material a much greaterdesulfurization can be effected without serious deterioration of theproduct by catalytic reactions. It is. important to have this inhibitioneffective all over the bed of the contact material, i. e., without zoneswhich are fully active.

The control of the activity of the contact material may at the same timereduce its capacity as a desulfurizing agent; but, because the catalyticactivities are decreased proportionally much more, the actualdesulfurization by my process is more complete, rapid and eiiicient than-by use of highly active catalytic desulfurizing materials, as is mademore clear below.

Although, according to my invention, the catalytic activities of thecontact mass are intentionally inhibited, e. g., by poisoning, they neednot be completely destroyed. It is an important advantage of myinvention that it provides a control for catalysis of high temperaturereactions in an oil by which a limited and selective hydrogenationand/or dehydrogenation may be utilized to improve the quality of theproduct as well as to facilitate the desulfurization. This limited andselective hydrogenation activity is retained, according to my invention,while the harmful phenomenon of decomposing hydrocarbons into theelements, hydrogen and carbon, is inhibited entirely or to the point ofinsignificance, even well above 650 F.

The chemical inhibitor which vI have found most satisfactory and mostadvantageous is the very sulfur which it is the purpose of the contactmaterial to remove from the oil. Other materials which have aninhibiting effect such as chlorine, bromine, iodine, selenium and/ortellurium may be used in small amounts with a somewhat similar effect.The criterion of value of such inhibitors for use in my invention is inthe difference in the degree to which they depress or suppress undesiredreactions disproportionately more than the desulfurizing activity orcapacity. These inhibiting materials may be retained, at leastpartially, on the catalytic mass during and throughout its regeneration;and insofar as they may be eliminated they are inexpensive to replace.Mercury and lead, and in general any metal which forms an alloy with thecontactor, will reduce the catalytic activity; such metals, however,tend to reduce the desulfurizing activity more strongly and are,-therefore,less ,desirable than the inhibitors previously mentionedabove.

A most advantageous process according to my invention is one in whichsulfur is used as the inhibitor; and the contact material, when it hasbecome more or less saturated with sulfur, is not regenerated to a fullyactive catalyst, but instead is regenerated by a. treatment controlledto leave a sufficient amount of sulfur in all parts of the regeneratedmass to still inhibit the catalytic activites when the regeneratedcontacter is again put into service.

The amount of sulfur or other inhibiting agent,

is not sharply critical. Withincreasing small amounts of sulfurdistributed in the contact surface, the catalytic activity of thecontacter is rapidly decreased while the desulfurizing activitydecreases only very. little. Later. as the surface approaches saturationwith sulfur, the desulfurizing activity drops more rapidly while thecatalytic activity decreases very little more. This differential isutilized according to my invention by operating between a minimum sulfurcontent, at which the catalytic activity, especially for decomposition,is already substantially below that of the pure metal, and a maximumcontent, at which hydrogen sulde would begin to form. It is important inthis process that no substantial part of the contact mass contain lessthan said minimum sulfur content during its use in the high temperaturesulfur absorbing treatment. In practice, however, parts of the contactormay be allowed to reach or exceed the maximum so long as subsequentlycontacted parts of the mass are well below the maximum so as to removeany hydrogen sulfide which might be formed in the sulfur saturated zoneof the contactor.

The amount of sulfur necessary to produce the inhibition which willprotect the product against deterioration will depend very much upon theuniformity of distribution of the inhibiting agent in the contactsurface, and upon the depth of the sulphur absorbing metal below theexposed surfaces. With a contacter such as is described below in thepreferred embodiment, I havefound that a most economical effect occurswith ay sulfur content in the neighborhood of 15%, based on the weightof the nickel, but if the sulfur is uniformly distributed an amount aslow as 5% or even 3% will give substantial protection. Preferably thesulfur content should be reduced to, at the least, vabout 20% at eachregeneration. With heavier coating of nickel on the carrier orespecially if nickel is used without inert carrier the percentages ofsulfur would be lower, since it is primarily the surface which isconcerned in this process. f

Within the general limits specified, the precise extent to which sulfuris present in the contactor when its use is begun will ordinarily dependupon cost considerations. Since the uniformity of sulfur distributionbecomes more important as the minimum sulfur content is approached, thecost of precautions necessary to assure uniformity will oset to someextent the savings which would otherwise result from longer operatingperiods made possible by lesser sulfur retention.

Regeneration with sulfur retention If air by which the sulfur is burnedfrom the aar-3,299

contactor is passedmrougnltne contacteren tinuously from one sidethereof toward'tl'ieotlierbe completely deprived of its sulfur, whilethe. part near the exit oi the gases may still retain a.

substantial part of its sulfur. If such a contactor were put into use ina high temperature desulfurizing treatment, such as is described below,the sulfur-free part of the catalyst would produce objectionablereactions, e. g.. of decomposition into hydrogen and carbon andexcessive hydrogenation.

In my preferred process, I assurethe retention of the necessary smallamounts of sulfur throughout the contactor, by the simple step ofremoval of the sulfur from the contactor under carefully regulatedconditions, especially of heat dissipation, such that the reaction canproceed as a self-sustaining reaction atl the given temperature only solong as the concentration of sulfur remains above that desired in theregenerated contactor. Thus, as soon as anypart of the contactor has itssulfur concentration reduced to the desired extent, the heat balance atits surface will be such as to terminate the reaction; and a residuum ofpoisoning sulfur will be retained upon that part of the contactorregardless of how long it may be necessary to continue the passage ofair and/or other oxidizing gas through the contactor for burning excesssulfur from other parts thereof.

It is important, moreover, that during this treatment the temperature ofthe contact surface should not be allowed to increase excessively andthat the temperature should advantageously be kept below about 1000 F.as measured by a thermocouple embedded in the contactor. Above about1000 F. the physical or chemical condition of the nickel or other sulfurabsorbing material at the surface may be altered so that it is lessactive for desulfurization.

Both the control of sulfur retention and the control of maximumtemperature, I have found can be most effectively secured by supplyingto the contactor a regulated mixture of air and steam at temperaturessubstantially below that at which the reaction with sulfur of thecontactor mass would occur and continue spontaneously after the sulfuris reduced to the concentration in which it is to be retained for thepurpose of inhibition. The temperature of these gases ordinarily shouldbe Well below 600 F.; and in practice I find it advantageous to supplyair at room temperature mixed with steam at a temperature as low as ispracticable while avoiding undesirable condensation, e. g., about Y250F. The use of steam I have found to have great advantage over any othergases known to me; and, although the nature of its action has not beenconclusively determined, I believe that the reason is that the steamserves both as a chemical cooling agent and as an oxygen containingagent for conversion of the suliide to the oxide, and perhaps has anaction also as a catalyst or promoter-at least it causes the reaction toproceed more rapidly at the relatively low temperatures used.

The reaction by which the oxygen of the air reacts with the sulfide,with formation of the metal oxide and sulfur dioxide, is an exothermicone-that is to say, it releases large amounts of heat-and since thisrelease of heat is concentrated on the thin surface layer, the physicalcondition of which is most important to the ling local overheating is avpeculiarly diicult one.

On the' otherlhand, the .reaction by which the Y. water vapor transfersits-oxygen tothe metal,

of the sulde and removes the sulfur ashydrogen sulfide is'an endothermicreaction-that is e to say, it can proceed only if heat or equivalentenergy is supplied from the outside. \In the process according to myinvention'this latter reaction also proceeds directlyupon the surface ofthe contactor; and since this surface tends to adsorb the water vapor,it will proceed whenever the necessary energy is available. Thus,according to my invention, the presence of the water on the surfaceserves as an automatic control for the temperature of the surface: assoon as the direct oxidizing reaction with air makes energy available,which ordinarily would be released in the form of objectionable heat,the water on the contactor surface, according to my invention,immediately utilizes that energy in its endothermic reaction, so thatthis energy may be transferred and consumed directly as chemical energywithout any serious danger of overheating the surface of the contactor.

The hydrogen sulde formed in this reaction is, of course, a combustiblegas, and to some extent atleast it may burn in the excess air or react`with SO: with further release of heat. I have found, however, that theheat thus released in the gases is relatively harmless, being largelycarried ofi' with the exhaust gases, and only being slowly transferred,if at all, to the contactor surfaces, whereas heat released in reactionsoccurring on the contactor surface may easily overheat and damage thatssurface. Any excess steam will serve by dilution to slow down suchburning of hydrogen'sulflde.

The action of the steam thus serves to keep the temperatures of thecontactor in a range near the lower limit at which the reaction with airproceeds spontaneously, and consequently, as soon as the concentrationof the sulfur on the surface is suitably reduced there will at first beless and less energy'available forthe reaction with water; and finally,the rate of heat generation in the reaction will fall below the rate ofheat dissipation from the contactor surface, after which the surfacewill soon be cooled below the temperature limit at which the reactionceases, and the residual sulfur will-remain in the contactor surface toserve as a catalysis inhibitor notwithstanding that the passage of airand steam is continued for the burning of other portions of thecontactor surface which at rst were receiving mostly the sulfur bearinggases from the preceding parts of the contactorand had had as yet nochance to react.

It is possible to effect a similar but less perfect control by dilutingthe oxygen vwith inert gases. This method of control, however, willinvolve a longer reaction time. It is possible to attain sufficientuniformity of sulfur retention merely by controlling the flow of theregenerating gases, especially by reversing the ow or changing itscourse as certain parts of the contactor approach a given sulfurcontent. If adequate distribution is maintained, the sulfur content maybe controlled merely by stopping the regeneration at the proper moment.

The process of preparation andregeneration of the contactor with controlof sulfur removal, and especially by temperature control through controlof chemical reactions, is claimed in a activity of the contactor, theproblem of controlcompanion application Serial No. 117,673, filedDecember 24, 1936. Y

The product of the oxidation treatmentis reduced with hydrogen, and thisshould occurv at a moderate temperature to avoid reduction ofdesulfurizing activity. I prefer to carry this out between 600 and 800F.

Another important feature which is made possible by my invention is theclose temperature maintenance throughout the cyclic process whereby thecontact mass, substantially throughout its use and regeneration ismaintained within a temperature range of, at most, a very few hundreddegrees. I have found that in this way the output of the apparatusrequired can be very greatly increased and that the activity of thecontactor can also be maintained over a much longer useful life.

Temperature of oil treatment 'I'he use of relatively high temperaturesduring the desulfurization of the gasoline is another important featureof my invention; and when such high temperatures are used the control ofcatalytic activity, according to my invention, is especially important.'I'he use of such high temperatures will greatly increase the rapidityof desulfurization and the efficiency of utilization of the contactor sothat with a given amount of contactor a much larger volume ofhydrocarbon oil can be treated and more sulfur can be ab-v sorbed fromthe oil by a given amount of the contactor. i

I have found also that a number of the more refractory sulfur compoundswhich occur in the hydrocarbon oils may be readily and substantiallycompletely removed by my contactor at temperatures above 700 F. andespecially above 750 F., without the occurrence of other undesirablereactions which might be expected at such temperatures in the presenceof a surface active contactor.

The most serious reaction which comes into prominence at these highertemperatures in the presence of the ordinary highly active catalyts isthat of decomposition of hydrocarbons into the elements carbon andhydrogen. Although this decomposition is often overlooked or confusedwith cracking, it is quite a different phenomenon, and one which needsto be carefully avoided. It is bad, not merely because of the waste ofthose hydrocarbons which would be destroyed by the decomposition, butalso, and even more important, because of the fact that products of thedecomposition would be deposited upon and blanket the surface of thecontact material so as to seriously impair or even to destroy itsability to perform effectively further desulfurization of the oil.

The metals nickel, cobalt and iron which are mostJdesirable for use inthe desulfurizing contactor are also most active in catalyzing thisdecomposition reaction at temperatures above about 600 F.

Such reactions as cracking, polymerization, hydrogenation anddehydrogenation' may, of course, proceed to some extent at thesetemperatures, and more rapidly with increasing temperatures, even in theabsence of catalysts; and these reactions may even be stimulated to someextent by the contactor used in my invention. It is in fact an importantadvantage of `my process that, by use of the inhibited catalyst, suchreactions may be promoted selectively and limited as desired. Thus,'forexample, one may have selective hydrogenation of objectionable, e. g.,gum forming, constituents and of the carbon linkages released by sulfurremoval, substantially without hydrogenation of desirable, e. g.,aromatic, hydrocarbons. Operating conditions may be chosen to favordesired products in accordance with well understood laws of chemicalreaction. Thus, an increase in the amount of hydrogen present with thehydrocarbons during treatment or an increase in pressure with sufiicienthydrogen will tend to increase hydrogenation. A high temperature withoutadded hydrogen or with very little hydrogen favors dehydrogenation andpolymerization. Lower pressure favors simple dehydrogenation, whereashigher pressure favors polymerization. The conditions of hightemperature and low pressure will bring into prominence the reactions ofdehydrogenation over those of hydrogenation. In the temperature rangeabove 850 F. the cracking reactions are strongly favored by temperatureincrease.

Hydrogen The use of hydrogen is important in my invention though notentirely essential. Without hydrogen or with too little the product maybe to some degree unstable, of high gum content and subject to seriouspolymerization; and moreover, the desulfurization will proceed moreslowly and in many cases will be less complete if hydrogen is not added.The presence of hydrogen apparently serves, as already described above,to satisfy the carbon linkages in the compounds from which the sulfur isremoved, and thus at once to facilitate the desulfurizlng reaction andto avoid the formation of unstable unsaturated products.

At higher temperatures such that considerable cracking occurs morehydrogen will be consumed, and unless a highly unsaturated product isdesired, more hydrogen should be supplied. (Such cracking in thepresence of my novel contactor is more particularly described andclaimed in' my companion application Serial No. 231,298. filed September23, 1938.) 'Ihe amount of hydrogen used is not sharply critical, butdepends upon the raw stock being treated` and the products desired. Ingeneral, straight run and highly paraflinic oils require less hydrogenthan cracked or other highly unsaturated oils; and treatment duringwhich cracking or reforming is combined with the desulfurizing willrequire more hydro- Een.

When treating oils for Diesel fuels by my process a relatively highconcentration of hydrogen is favorable.

-I have found that the use of a large excess of hydrogen tends tostimulate hydrogenation reactions which are undesirable in treatinggasoline, and which cause an uneconomic consumption of hydrogen in suchtreatment, but which may be desirable, e. g., for Diesel fuel. Suchexcess of hydrogen tends also to form hydrogen sulfide with' high sulfurstocks, even with a contactor which is still capable of satisfactory usewith a more suitable proportion of hydrogen. Ordinarily, for the averagehigh sulfur raw stock, an addition of 1% of hydrogen, based upon theweight of the oil mixed therewith during the treatment, will beadequate, and in general the amount of hydrogen introduced with the rawstock will be increased with increase of the amount of sulfur which `isrequired to be removed. e. c.. 0.25% to 2.0% of hydrogen. but evenserious objection.

Even when an adequate amount of hydrogen is used there may occursimultaneously both hydrogenation of undesirable and gum forming2,273,299 ve times this amount may be used without net consumption, i.e., the difference between the amount supplied and the amount remainingafter the treatment. v-

The hydrogen used need not be of high purity.

Specific examples In .the accompanying drawing I Ahave shown also a.diagrammatic arrangement of apparatusV serving also as a process owsheet, illustrating a preferred embodiment of my invention. It should beunderstood that the drawing and the description given herewith and thevarious alternative structures and procedures suggested herein are notintended to be exhaustive nor limiting of the invention, but on thecontrary, are chosen for purposes of illustration and explanation inorder that others skilled in the art may so fully understand theinvention and the principles thereof and the manner in which itisapplied in practice that they'will be able to vary and modify it innumerousways and toembody` it in numerous forms each as may be bestsuited to the conditions and requirements of a particular use.

Referring to the drawing, the raw stock is supplied through' the pipeline I0, the pump II, the

heat exchangers I3 and I4, and the tube heater and still I6. 'Ihehydrogen, either from the supply line I1 `or from the recirculating tankI8 isv compressed to pressure required in the system by the compressorI9 and then passed into the raw stock supply line, where it is mixedwith the raw stock and with it passed through-the heat exchangers I3 andI4 and into the tube heater I6.

The mixture of raw stock and hydrogen passes from the tube heaterthrough the plp`e20 into one of the three reaction chambers 2I A, B orC. These reaction chambers are substantially identical, and each is lledwith a contact mass which may consist in this preferred example of apumice carrier, e. g., in pieces averaging about Vs v.to 1/2' inch indiameter. A pumice stone having about 0.38 apparent speciiic gravity issuitable for this purpose, but the numerous other carriers already knownin catalytic work may be used likewise. The pumice grains areimpregnated to 'cover the surfaces with nickel to the extent of about10% of nickel based on the total weight of the contact mass; andabout 1%of aluminum oxide may be added. The aluminum oxide helps topreventrecrystallization of the nickel during regeneration', which wouldreduce th'e sulfur absorbing surface, and permits higher regenerationtemperatures. It also absorbs water so as to supply it locally duringregeneration to offset the exothermic effect o! the regenerationreaction. The nickel and aluminum vmay be applied to .the pumice assulfate solution which is subsequently precipitated, e. g., with sodiumcarbonate, and/or dried, or as fused salts, e. g., fusednitrates; ineither case the deposited salts may be roasted carefully to the oxidesand the nickel oxide reduced to metallic nickel at a temperature lowenough to assure high surface activity, e. g., below 650 F.

" The contact mass should be suitably 'treated for inhibition ofcatalytic activity beforeregulari use. Thiscould be done, e. g., bypassing gases or ol containinghydrogen sulfide mass. v

'Ihe contact chambers 2| are connected to the supply line 20 by valvedbranch pipes 22; and a manifold 24 is provided for connecting the top ofany chamber with the bottom of any other chamber through the valvedconnections 23 and 25 re-y spectively. Any of th'e chambers A. Bor C maybe'connected through'the valved connections 26 to an off-take manifold21. From the off-take manifold 21 the treated vapors pass to a suitableoil separating and recovery system.-

. As one example of the use of this apparatus for the process of myinvention, I have taken as raw stock a naphtha from a high sulfurMexican crude. This naphtha contained about 0.67% sulfur, had a boilingrange from about F. to 450 F.` This raw stock was fed intoy the systemby the pump II. Hydrogenat a rate slightly below 1% (by weight) that ofthe raw stock was supplied by the compressor I9. The `pressure wasmaintained inthe system land especially in the reaction chambers about200 lbs. per square inch.

The mixture was preheated to a temperature of about 830 F. by the heatexchangers I3and I4 and the tube heater IB. Assuming that the reactionchambers Av and B are operating in series, 'and C is being regenerated,the valved connection 22 to the reaction chamber -A will bel open andthe corresponding connections 22 to the chambers B and C will be closed.Likewise,-

and hydrogen passes into-the top of the cham,

ber A and through the contactor therein, which will be ata temperature alittle above 800 F., and out through the connection 23 and the manifold24 into the connection 25 of the chamber B and thus into the top of thesecond reaction chamber B,- from which the treated product passes oi'fthrough 26 Iand 2l for cooling, separation and further treatment.

The rate of flow is regulated to give a contact period in the twochambers A and B sufficient to effect the desired desulfurization.

In the reaction chamber A the vapors have encountered a contactorrelatively high in sulfur content. In the chamber B the vapors encounterthe most recently regenerated contactor and one, therefore, whichalthough inhibited by its retained sulfur content, is more active as adesulfurizing agent. Thus, when the vapors have passed through thesecond chamber B the desired chemical treatment is completed.

By suitable insulation of the reaction chambers and connections the heatof the vapors is conserved and no other heating is required. However, ifless insulation is used or if the fresh or freshly regenerated contactorin the second reaction chamber is at lower temperature when first putinto service, the temperature in a part or all of the second chamber maybe much lower. There is no objection to this except that theeffectiveness ofthe cooler contact massr is reduced.

The vapors which leave the reaction chamber B through the connection 26and 21 are comthrough the This is accomplished in the present case bypassing the efiluent from 'the reaction chambers through a heatexchanger 2l and a water cooler 20 into the gas separator and scrubber30 where condensible and soluble hydrocarbons are re- Y moved fromresidual hydrogen and the residual hydrogen bled ofi and collected inthe tank Il for recycling in the process.

With such recycling, in the particular example mentioned. about 0.18% ofhydrogen (based on the weight of the oil) is consumed. including lossesin the operation and must be supplied from outside sources when residualhydrogen is recycled.

The oil passing from the gas separator and scrubber 30 is again heatedby the heat-exchanger 28 and passes from thence with reduction oi'pressure by the valve 32 into the fractlonating tower 35 where anyheavier hydrocarbons are separated and collected in the bottom of thefractionating column, from which they are recirculated by a pump 33 tothe scrubber Il, passing rst through the heat exchanger Il and the watercooled heat-exchanger 3|. Il there should be an excess of bottoms it maybe drawn of! to storage through the line 36.

A steam heating coil 31 may be provided in the bottom of thefractionating column for indirect heating, and live steam may besupplied through the pipe 38.

The desired product comes from the fractionating column 35, passesthrough the heat exchanger I3, where it serves to preheat the raw stockand hydrogen, and advantageously through a final cooler 39 and apressure release valve Il to a gas separator and receiver 40 and iinallyinto a gasoline storage tank (not shown). Tail gases and water separatedfrom the gasoline are drawn of! from the separator 40 through theconnections shown.

The following comparison of the same stock used in the example justdescribed. i. e., naphtha from high sulfur Mexican crude, treated byordinary methods and by my process as just described will illustrate theadvantage of my process:

Raw stock My product lo n. m M

acid/bbl. acid/bbl Chemical treat- No treat- Vapor phase Acidcaus- Acidcausment. me c o n t a c t tic doctor tic doctor.

described Treatment loss.. l2.7%. 12.2%. Gravity .1.. 49.1. Color(Saybolt). +28. t lw' ur Gum (AsTM) 0.4 mi--- 0.a m. Initial boiling 1722m".

point. 7 228 244 w". so :414 320. 90% 380 379 390. End point 438 442.

The sample of my product tested was a composite blend of ten samplestaken at equal intervals during the entire period of operation of onepair of reaction chambers until one was ready for regeneration.

'I'h'efadvantage as to octane rating and lead susceptibility is shown bytests made on Metallic nickel-- 2.5%

of these same products with casing head gasoline:

The iniluence of the temperature is shown below in a series ofexperiments with separate samples of the same California crackeddistillate using the same contactor as was used with the Mexican naphthaabove referred to. 'Ihe amount of nickel was 2.5% based on the oil, and1.06% hydrogen was introduced, the time of reaction being about 12minutes in each case:

Temperature, F.

Rswsroek 000 100 820 Yield by weighs pernz.. oas 98.0 08.8GravityA.P.I.at00.....degrccs.. 49.7 50.5 51.1 51.9 sulfur .pernr.. 0.650.31 0.19 v0.01

The iniluence of the amount of contactor relative to the oil is shownbelow in a series of experiments in a batch operation with the same rawstock; the amount of hydrogen introduced and time of contact being asshown above, and the temperature of reaction being about 820 F.:

1.4% Raw stock Sulfur 0.07% 0.19% 0.66%

Another example follows in which cracked California heavy naphtha wastreated at high temperature in the reaction chambers for production oflow sulfur gasoline:

condition of treatment t The analysis of these stocks is given below:

Raw stock Finished gaso- VSemiprodue't une n Co per-dish gum. In tialboiling point. Endboillngpoint. Octane No The lead susceptibility ofthis product (like au products'resulting from my process) was greatlyblends 7s improved as compared with that of the raw stock.

' ejer/3,299

No acid treatment is necessary in my process' unless the raw stocktreated has nitrogen bases or phenols. These compounds are only partlyattacked by the desulfurization treatment according. to my invention,and for their complete elimination a small amount of diluted acid, e.g., 80% strength may be used and followed by a caustic wash. a

The chemical treatment of the semi-product in the example just givenrequires that the oil from the separator 30 should be drawn oi! to thetreating tanks (not shown) before passing on to the fractonator 35. Itis also advisable in this case to use a separate scrubber for the gasesfrom the separator, becausethese gases contain a much larger proportionof hydrocarbon gases as a result of the cracking and require. therefore,a larger amount of scrubbing oil which it is not desirable to mix withthe condensed product. Instead of the oil scrubber, active charcoal canbe used.

Two additional examples are given below in parallel columns:

Treatment of contact material R ene-.ration medium Air and steam air andsteam Rglgzeneration temperaturem.. 70800 F. 7008l0 F. Reduction mediumHydrogen Hylglmgteyn of 85% Reduction temperature 450-800 F. 400- F.

` California late Raw stock:

Gravity A. P. I. at F Color :sa ot corrosive. 390 F.

0.0l o Not corrosive--. 427 F End Aromatics in both cases remainedunchanged within limits oi analytical error.

As anv example of heavier raw stockpMexlcan (Panuco Field) kerosene wastreated under con.v

ditions similar to those described in the rst example with Mexicannaphtha, but at somewhatv lower temperatures (730-8l0 FJ. 0.21% byweight hydrogen was'consumed. Results are giveny below: i

Raw stock` My process sa Ilia 0K a 51 o. om

All other tests (including burning tests) classed my product as premiumkerosene.

The raw stock ordinarily need not be distilled and fractionated beforethe desulfurization treatment; but such treatment is advisable withweathered and a'sphaltic oils in order to remove gummy and tarryconstituents which might deposit on the contactor and impair furizingability.

If more sulfur can be tolerated it may be more economical to operatewith more rapid flow, or

shorter path of travel through the contactor or with less hydrogen.

During the desulfurizing operation the third reaction chamber C may beundergoing a process of regeneration. Assuming that the reaction chamberC has previously been utilized in the desulfurizing series and has justbeen segregated from the flow of vapors, itscontact mass will be at atemperature inthe neighborhood of `800 F., and its reaction mass will belargely converted to sulfide.

As apreliminary` to the regeneration it is ordinarily desirable to cleanout thel reaction cham ber by closing the valved connections 22, 23, 26

this cleaning treatment may pass off with the waste gases through thevalved connection 4 1, the manifold 45, and condenser 49, to theseparator 50 designed to separate the hydrocarbons from the condensedwater. Since these hydrocarbons contain hydrogen sulfide formed byaction of the steam on the contactor they are not mixed with the treatedproduct, but they may be mixed with the raw stock if desired.

As soon. as the hydrocarbons and any other vaporizable materials aresufliciently cleaned. out of the reaction chamber the exhaust isdiverted through the outlet 45'. At the same time the steam flow throughthe valved connection 43 i-s decreased and at the same time air is blownin from the air line 42 through the manifold 44 vand the valvedconnection 46. Since at this stage the contact mass within the chamber Cis still at a temperature at`which energetic oxidation of the sulde(which I sometimes refer to as combustion) occurs spontaneously, suchreaction f will begin to take place at once. By a suitable control oftheproportion of steam supplied from the line 43 the temperature within thereaction chamber C may be suitably controlled.

More steam than air is ordinarily to be used at the start and less steamor even air alone may be used near the end of this regenerating step. l

If the steam and air are properly proportioned, the reaction willterminate automatically as soon as the desired degree ofdesulfurizationhas occurred. As soon as the temperature drops, e. g.,'to about 650 F., the oxidation treatment may be considered completed formy purpose. The temperature in some zones may drop considerably lower,e. g., to about 500 F. or lower and this condition can be improved byreversing the flow of steam, and/or air or hydrogen or other gas usedduring regeneration: and also this part of the mass may be heated by theoil through the connection 6i, and the ow of hydrogen thus continueduntil the desired reduction is attained.

It is not essential that the reduction in this its 'aesinstage should becomplete, and in fact the oxidized material may be reduced by turningthe flow of hydrocarbon vapors and hydrogen directly into the oxidizedcontact mass. '1111s latter procedure, however, is not recommended,since it consumes hydrogen which should be available for reaction withthe oil; and if it is adopted a much larger amount of hydrogen should besupplied to care for the reduction of the oxide. Even with thisadditional hydrogen, however, the oxide may cause a temporary deficiencyof hydrogen in parts of the vapors so that the results may beunsatisfactory with respect to polymerization, stability and gums. It isfor this reason especially that the reduction is recommended.

When the desired reduction has been effected the reaction chamber C isready for use in the process; and it may, therefore, be cut into theseries once more by closing its valved connections 46 and 41 and openingthe valved connections 25 and 26. At the same time the chamber B will bechanged from the second in series to the first in series by closing itsvalved vconnections 25 and 26 and opening its valved connections 22 and23, and the reaction chamber A will then be segregated from the ow ofvapors by closing its valved connections 22 and 23 and its contact massregenerated as already described in connection with the chamber C.

Thus, each chamber in turn when regenerated serves first as the secondchamber of the series, then as the ilrst chamber of the series andduring a third period is segregated from the ow of vapors and itscontact mass regenerated; while the flow of vapors-i treatedcontinuously in an initial contacter which is partially exhausted, andfinally in a freshly regenerated but at least partially inhibitedcontacter.

During the period of treating the oil the heating of the contact mass isassured by the hot vapors coming from the pipe still until at the end ofthis period the contact mass is above about 800 F, sometimes evenconsiderably higher, e. g. 950 F.

During the steaming out treatment the temperature drops somewhat lower,but with the admission oi' air a further heating occurs which iscontrolled by the regulated addition of steam to carry the temperatureup to about 900 F.

Upon termination of the reaction, the air and steam lower thetemperature of the mass again, e. g., to a temperature of about 700 F.;and during the reduction treatment the temperature ordinarily is notvery greatly changed.

The pressure chosen may be maintained throughout the desulfurizingoperation without change, the burning of the sulfide may with advantagebe at atmospheric pressure, and in that case the pressure may begradually brought back to the operating pressure by the hydrogen usedduring the reducing step.

Although I have used for these examples pressures of 200 lbs. and 500lbs. per square inch and I have found pressures from 1D0-1000 lbs. persquare inch most suitable for the treatment of these particular oils;nevertheless, a widel range of pressure is permissible without departingfrom my invention.

Although I have shown in eachof my examples, three reaction chambers, itwill be understood, of course, that the number will be determinedprimarily by engineering considerations. The ilow of gases in thechambers may, of course, be upward or downward.

Hydrogen, which in the example is added to the liquid oil, may with someadvantages be added to the vapors, e. g., in the line 20, or at otherpoint or points in the line ofiiow.

Although I have speciiied in each of the examples the regeneration ofthe contact mass by treatment with air and steam and subsequentreduction with hydrogen, my invention is not limited to this particulartype oi treatment and in general I may use any of the methods availablefor regenerating catalysts provided that they are controlled to retain asmall amount of poisoning, or that the regenerated contacter isotherwise treated to control its catalytic activity.

These various alternatives have been mentioned to illustrate thenumerous variations which can be made without departing" from the scopeof my invention, and it will be understood that these are only a few ofthe variations which are possible. Y

Thisapplicationisacontinuationinpart of the prior copending applicationsSerial Nos. 231,298, filed September 23, 1938; 117,673, filed December24, 1936; 94,578, led August 6, 1936; and 60,466, filed January 23,1936.

What I claim is:

1. A process of desulfurizing sulfur-bearing hydrocarbon oils whichcomprises passing such oil thru 1a porous contact mass having anextended surface comprising free metal of the class consisting ofnickel, cobalt and iron, and having sulfur distributed substantiallythroughogt said surface acting as an inhibitor of its catalytica'ctivity, segregating at least a part of said mass from the oil flowafter it has taken up a substantial amount of additional sulfur from theoil, removing such additional sulfur by oxidization at temperaturesufiiciently low to avoid substantial impairment of desulfurizingactivity, terminating the oxidation reaction in each part of the masswhile sufficient sulfur remains in said mass to substantially poison itscatalytic activity, substantially reducing the oxide formed in theoxidation step, and again in a repetition of the process utilizing thecontact mass thus reformed.

2. A process of desulfurizing sulfur-bearing hydrocarbon oils'whichcomprises passing such oil thru a porous contact mass having an extendedsurface of a metal of the class consisting of nickel, cobalt and iron,which contact mass contains at least about 15% of sulfur, based on theweight of said metal, segregating at least a part of said mass from theoil flow after it has taken up a substantial amount of additional sulfurfrom the oil, removing such additional sulfur by oxidization at atemperature sumciently low to avoid substantial impairment ofdesulfurizing activity, terminating the oxidation reaction while atleast about 15% of sulfur based on the weight of said metal remains insaid mass to substantially poison its catalytic activity,

, reducing the oxide formed in the oxidation step while substantiallyretaining said sulfur, and again utilizing in a repetition of theprocess the contact mass thus reformed.

3. A process of desulfurizing sulfur-bearing hydrocarbon oils whichcomprises passing such oil thru a porous contact mass having an extendedsurface of a metal of the class consisting of nickel, cobalt and iron,which contact mass contains at least about 5% of sulfur based on theweight of said metal distributed throughout substantially all parts ofthe mass, segregating at least a part of said mass from the oil flowafter it has taken up a substantial amount of additional sulfur from thecil, removing such additional sulfur by oxidization at a temperaturesuillciently low to avoid substantial impairment of desulfurizingactivity, terminating the oxidation reaction while at least about ofsulfur based on the weight of said metal remains ineverypartofsaidmstosuhstantiallypoison its catalytic activity, reducingthe oxide formed in the oxidation step while retaining sulfur therein,and againutilizing. the contact mass sulfur by oxidization at atemperature sum-- ciently low to avoid substantial impairment ofdesuifurizing activity, terminating the oxidation reaction while atleast about 3% oi' sulfur based on the weight of said metal remains insaid mass to substantially poison its catalytic activity, reducing theoxide formed in the oxidation step but retaining at least about 3%sulfur base on the weight of said metal, and again utilizing the contactmass thus reformed in `a repetition of the process.

5. A process of desulfurizing sulfur-bearing hydrocarbon oils whichcomprises vaporizing such oil and superheating its vapors, passing saidvapors through a porous vmass of contact material having an extendedsurface of a metal of the class consisting of nickel, cobalt and ironand having an inhibitor distributed substantially throughout saidsurface, continuing such passage until at least a part ci' the contactmass is substantially converted to sulfide by sulfur taken up from theoil, segregating from the oil at least a part of the contact mass whichhas been thus converted to sulde, passing through the contact mass anoxygen-containing gas adapted to ccnvert said sulilde to oxide, passingthrough said mass a reducing gas adapted to reduce said oxide to themetal, and again utilizing the reduced mass for desulfurizaticn bypassing the oil vapors therethrough, which process ls characterized bythe fact that the temperature oi the contact mass during each of saidsteps of the entire cycle is within a range between approximately 600 F.and 1000 F., and said material is at all times maintained in itsextended surface condition, and an inhibitor is at all times maintainedin and distributed throughout said material sufficient to avoidcatalytic decomposition of the oil and blanketing of the catalyst withcarbon formed thereby.

6. A process of desulfurizing sulfur-bearing hydrocarbon oils whichcomprises vaporizing such oil and superheaiing its vapors, passing saidvapors through a porous mass of contactmaterial having an extendedsurface of nickel poisoned with sulfur in substantially every part ofthe mass, continuing such passage until at least a part of the contactmass is substantially converted to sulfide by sulfur taken up from theoil, segregating from the oil at least a part cf the contact mass whichhas been thus converted to sulnde. passing through the contact mass anoxygen containing gas adapted to convert said sulfide to oxide, passingthrough said mass a reducing gas adapted to reduce said oxide to themetal, and again utilizing the reduced mass for desulfurization by theoil vapors therethrough, which process is characterized' by the factthat the temperature of the contact mass during each of said steps ofthe entireV cycle is within a range between approximately 700 F.'

and 900 F. and said material is at all times maintained in its extendedsurface condition and sulfur poisoning is at all times maintained insub# stantially every part of the mass suiilcient to avoid catalyticdecomposition of the cil and blanketing of the catalyst with carbonformed thereby.

7. The process as defined in claim 5, in which the passage of the oilthrough the contact mass is continued until at least the part of thecontact mass which is to be segregated is so far converted to sulfidethat it can be oxidized spontaneously by air at room temperature andwithout otherwise raising its own temperature. air is supplied to saidmass for oxidation of the sulfide, and the temperature of the contactmass during said oxidation is kept within said range and overheatingisprevented by a regulated supply of ste'am thereto during saidoxidation.

8. The process as defined in claim 5, in which the passage of the oilthrough the contact mass is continued until atleast the part of saidcontact mass which is to be segregated is so far converted to sulfidethat it can be oxidized spontaneously by air supplied at roomtemperature, and, without otherwise raising its own temperature, air issupplied to said mass at a temperature lower than that at whichspontaneous combustion of the sulfide. and the temperature of the massduring the' oxidation is kept sulciently low that the reaction stopsspontaneously by decrease of the sulde concentration before the sulfurpoisoning of the catalytic activity of the mass is eliminated.

9. The process of treating petroleum oils for production of improvedmotor fuels which comprises passing the oil at temperature above F., atwhich catalytic decomposition of hydrocarbons into elements could occur,and in the presence of hydrogen, over and in intimate contact with afree metal selected from the class consisting of nickel, cobalt and ironin extendedsurface condition, said metal at all times during saidtreatment having a catalytic-inhibiting substance distributed oversubstantially its entire surface in amount sufficient to substantiallyavoid the decomposition of hydrocarbons into elements, which wouldotherwise occur and at least some of said free metal remaining exposedto the oil at all times during said treatment.

l0. The process of producing doctor-sweet products of reduced sulfurcontent from sulfur containing hydrocarbon oil which comprises passingsuch oil in vapor phase with addition of hydrogen at temperature above700 F. at which catalytic decomposition of hydrocarbons into elementscould occur and through a contact mass comprising a porous carrierhaving free metal selected from the class consisting of nickel, cobaltand iron extended on its surface in physical condition adapted to giveit high surface activity but at all times during said treatment havingsulfur distributed substantially throughout said surface as an inhibitorfor the catalytic activity thereof and at least some of said free metalremaining exposed to the oil at all times during said treatment.

ANTONI SZAYNA.

' OERTIFIOATE oF CORRECTION.

Patent no. -275,299. February 17, 191m.

" ANTONI snm.

It is hereby certified that error appears inv the printed specificationofthe above numbered patent 'requiring correctionas follows: Page 6,first colmn, lines 5l te 5h, in the heading to the table, for "Acidtreated 2O 1bs.'ac1d/bb1." read --Acid' treated 25 lbs. sc1d/'bb1.; page9, first column, une 28, clam h, for base read based; and that the saidLetters Patent should be read with this correction therein that the samemayl conform to the record of the case in the Patent Gffice.

Signed and sealed t'his 21st day of April, A. D. 1914?..

Henry Van Arsdale, (Seal) 4 Acting Commissioner of Patents.

